Rod grip



ROD GRIP Filed June 10, 1924 11|' T1 i I i I I .lm/enror:

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Patented Nov. 19, 1929v UNITED STATES WILLIAM D. SHAIEFER,

' non Application led June 10,

This invention relates more specifically to a gripping device designedto be employed in frictionally connecting the upper end of Well i pump rods to their reciprocating mechanism.

The purposes of my invention are to provide a pump rod gripping device that will effectually grip the rod without roughening, or otherwise injuring its surface; that mav be M Vquickly secured to and removed from aurod 10' when it is desired to change its position; in

which its gripping or clamping members are so arranged and constructed that heavy or unusual loads may be safely imposed thereon without endangering a slippage of the rod orthe gripping elements.

My invention broadly comprises a cylindrical body member provided with a cylindrical concavity extending from the upper end downwardly and terminating adjacent zo the lower end, the bottom wall of the concavity being provided at one side of its centralvertical axis with a vertically disposed circular bore, a segmental recess being Lformed in the wall of the concavity and opening into the circular bore, a slip member having a longitudinally disposed concavity segmental in cross section, and set screws passing through the body member and engaging Athe slip to Vforce the same into frictional engagement with the rod to be gripped when the same is passed through the circular bore of the body member.

In the accompanying drawings I have illustrated a preferred embodiment of my invention, it being understood however, that no limitation is necessarily made tothe pre-V cise structural details therein exhibited, but various changes, alterations and modifications may be resorted to within the scope of my invention when desired.

Fig. 1 is a side elevation of a gripping device embodying t'he features of my invention suspended from the end of a wallging beam, the. polished pump rod being held in gripped relation.

orv Bami, CALIFORNIA GRIP 1924. serai No. 719,224.

Fig. 2 is a central vertical section through. thel grip showing a rod mounted therein in gripped position. Y

Fig. 3 is a top plan view with a rod gripped therein.

Fig. 4 is a top plan View with therod slip removed therefrom. Y

Referring moreparticularly to the drawings, 5 designates a substantially, cylindrical body member, provided with a cylindrical concavity l6- that extends downwardlyy from the upper end and terminates adjacent the. bottom wall 7the concavity 6 being disposed to one side' of thecentral vertical axis `of the body member.'A The bottom wall 7 is provided with a vertical circular bore 8, for the passage therethrough of vthe upper end of thepump rod 9, that is to be engaged, and Vheld by the grip. `Formed in the cylindrical wall of the concavity 6 and opening into the bore 8, is a longitudinally disposed recess 10, segmental in cross section, the distance between the verticaledges 11, 12, of the recess being less than the diameter of the pump rod. Disposed in the concavity 6, between the pump rod 9, and the wall of the concavity is a slip member 13, provided with a vertically Vextending groove 14,segmental in cross section, similar: in all respects to the recessformed in the thin 'cylindrical wall 15 of the body member, the distance between the vertical edges 16,17, being substantially the same' as the ldistance between the edges 11, '12,y of the verticallrecesslO. `Slip member 13 is provided'on its'peripheral surface with a vertically extending ilattened portion 18, oppositely disposed to groove 14. rv IBody. memberr 5 is provided inits cylindrical sidewall withfa pair of threaded bores 20', 21, opening into the concavity 6, in which are mounted set screws 22,23, the bearing ends of the screws abutting against the flattened pertionV 18 of the slip member to firmly clamp thepump rod 9 between the vertical edges 11, 12,- oiffthe recess 150, and the vertical Ledges 16,

17, of the groove 14 formed in the slip member. As the bore 8 of the body member 5 is slightly larger in diameter than the diameter of the pump rod, and further, as the radii of the recess l0 and the groove 14 are less than t-he radius of the pump rod, it will be clear that the only portions of the recess 10 and groove 14 that contact with the rod are their vertical edges.

It will be apparent from the above that by forming grooves inv the wall of the concavity and in the slip member, that the rod will be held in gripped relation solely by the vertical edges of the recess and groove, and as the set screws are tightened a wedging action will be set up, which action greatly increases the frictional grip on the rod. y

Trunnions are formed on the body member for the purpose of pivOtally attaching the lower ends of a hanger strap Q6, that is secured to one end of a walking beam, it being understood that other types of grip suspension means may be employed if desired. The bottom wall-7 of the body member provides a support or abutment which will prevent the slip member from moving independently of the grip.'

In actual practice I have ascertained that my improved gripping device in pulling tests will develop a greater gripping action thanV grips utilized for a similar nature now on themarlet. In a laboratory test conducted by ,Competent engineers a polished steel rod of 11/8 inches in diameter, was inserted in my rod grip and the set screws were tightened by applying a Trimo wrench thereto; A ten-- sile load on the polished rod was then applied until it slipped, it requiring a maximum load of 39,300 pounds before a slippage occured.

y The above laboratory test developed the fact that my improved gripping mechanism sustained a load of nearly 10,000 pounds in excess of the maxi-mum loads sustained by other well known grips in similar tests.

It will be understood that my device is not designed to be used exclusively in connection with polished rods of oill well pumps, but is readily adaptable for use wherever a 'triction hold is desired on a round bar or cable,

What I claim is:

In a rod grip, a body member having a cylindrical recess extending downwardly from its upper end, the bottom wall of Said recess being provided with a circular bore therethrough, the wall of said recess'having a longitudinal groove formed therein and opening into the circular bore formed in the bottom'wall of the body member, the side edges of said groove forming rod engaging edges, a slip member provided with a longitudinal groove segmental `in cross section,said slip member being normally supported by the bottom wallof the recess, the edges of said longitudinal groove forming rod engaging hereunto subscribed my name this 1st day of May, 1924.

WILLIAM D. SHAFFER. 

